Refrigerated trailer and method for same

ABSTRACT

The present invention relates to a refrigerated trailer for storage and transport of refrigerated products such as perishable food. The refrigerated trailer comprises an insulated box with a side door; a refrigeration unit for cooling air inside the insulated box, the refrigeration unit including an engine for supplying mechanical power to the refrigeration unit, batteries, and a compressor operatively coupled to the engine; an inverter electrically coupled to the batteries for supplying AC power; and an air curtain unit located above the side door, the air curtain unit including fans operating on AC power from the inverter, wherein the fans blow internal air downwardly over the door opening to limit air exchange between the insulated box and the outdoors.

FIELD OF THE INVENTION

The present invention relates to transportation equipment and systems, and more particularly to means and methods for transport of refrigerated products such as perishable food.

BACKGROUND OF THE INVENTION

The refrigerated food delivery industry needs to keep the temperature within refrigerated trailers somewhat constant. This is often difficult because each time the refrigerated trailer door is opened, warm air migrates from the exterior of the trailer into the refrigerated trailer and increases the temperature inside the trailer. The increase in temperature in the refrigerated compartment leads to several potential problems including destruction of the products within the trailer and increased energy costs to maintain the temperature within the trailer.

A conventional method to reduce the migration of external air into the refrigerated trailer is through the use of strip curtains. Strip curtains consists of long, plastic strips that are hung from the top of the door opening and hang down to the trailer floor. Although strip curtains are commonly used within the refrigerated trailer industry, they do have significant drawbacks. Often, the strip curtains can become wedged between a pallet that is being transferred into/out of the trailer and the doorway, creating an obstacle for entry into the trailer. This obstacle results in the curtain often being thrown up and over the doorway by drivers who become frustrated by the interference the strip curtains cause—thus eliminating the effectiveness of the strip curtain. Also, strip curtains are easily ripped, torn, or cut off. Furthermore, the strip curtains reduce visibility and can lead to safety concerns for the individual who is entering/exiting the refrigerated trailer.

Finally, strip curtains act as a surface to accumulate large amounts of condensation which can lead to several problems. First, this condensation reduces visibility through the strip curtains. Second, this condensation often drips onto the floor of the trailer where it refreezes and leads to hazardous conditions for an individual walking into the trailer. Third, the condensation leads to increased humidity in the trailer. This increased humidity can lead to a loss in integrity of the products within the trailer, or on the actual boxes holding the products. Over the past few years, the thickness of cardboard boxes has reduced significantly, mainly due to a push to used recycled products and to reduce waste. The decrease in box sturdiness coupled with increased condensation within the refrigerated trailer leads to boxes that can easily rip or tear. Ripped or torn boxes could potentially destroy the products within the boxes, thus increasing costs to the carrier.

Although strip curtains are useful for reducing the migration of warmer, outside air into refrigerated trailers, there are several problems associated with their use. It would be extremely advantageous to reap the benefits of the strip curtains without suffering from their associated problems.

SUMMARY OF THE INVENTION

The present invention discloses a refrigerated trailer comprising an insulated box having a door opening and a side door associated with the door opening; a refrigeration unit for cooling air inside the insulated box, the refrigeration unit including an engine for supplying mechanical power to the refrigeration unit, batteries, and a compressor operatively coupled to the engine; an inverter electrically coupled to the batteries for supplying AC power; and an air curtain unit located above the side door, the air curtain unit including fans operating on AC power from the inverter; wherein the fans blow internal air downwardly over the door opening to limit air exchange between the insulated box and the outdoors.

According to another aspect of the invention, the refrigerated trailer further comprises a thermostat connected to a sensor that senses ambient temperature, wherein the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature. Another aspect of the invention comprises the refrigerated trailer wherein the inverter is located outside the insulated box near the refrigeration unit.

Yet another aspect of the invention encompasses the refrigerated trailer wherein the insulated box contains multiple compartments, each compartment separated from an adjacent compartment by an interior wall. In a preferred embodiment, the interior walls are movable, whereby sizes of the compartments are adjustable. In a more preferred embodiment, the insulated box includes a freezer compartment and a cooler compartment, each one of the freezer compartments and cooler compartments having a side door. In a still more preferred embodiment, the freezer compartment is at the front of the insulated box and the cooler compartment is rearward of the freezer compartment. In another embodiment, each compartment includes a thermostat connected to a sensor that senses ambient temperature and each compartment includes an air curtain unit whereby the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature. In another embodiment, one compartment includes a thermostat connected to a sensor that senses ambient temperature and one compartment includes an air curtain unit whereby the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature.

In another embodiment, the insulated box includes a third compartment rearward of the cooler compartment, the third compartment having a side door. In a preferred embodiment, the freezer compartment is at the front of the insulated box, the third compartment is at the back of the insulated box, and the cooler compartment is between the freezer compartment and the third compartment. In a preferred embodiment, the refrigerated trailer contains three side doors on the left side of the insulated box and one side door on the right side of the insulated box.

The present invention further discloses a refrigerated trailer wherein the fans of the air curtain unit are disabled when the side door is closed. A preferred embodiment of the present invention further discloses the air curtain unit located inside the insulated box.

The present invention further discloses a method of maintaining temperature and humidity inside a refrigerated trailer, comprising the steps of providing an insulated box having a door opening on a side of the insulated box and a side door; refrigerating air inside the insulated box, including operating a refrigeration unit that includes an engine, batteries, and a compressor operatively coupled to the engine; inverting DC current from the batteries to deliver AC power to fans of an air curtain unit located above the side door; blowing internal air via the fans downwardly from above an opening in the side door to limit air exchange between the enclosure and the outdoors; sensing an outdoor temperature; and disabling the fans if the outdoor temperature is below a preset temperature. A preferred embodiment comprises disabling the fans of the air curtain unit when the side door is closed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a refrigerated trailer illustrating a preferred embodiment of the present invention;

FIG. 2 is a schematic elevational view of a portion of the trailer of FIG. 1; and

FIG. 3 is a flowchart of components of the preferred embodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 shows a refrigerated trailer 10. A refrigerated trailer 10 includes an insulated box 12, a refrigeration unit 28, an inverter 38, and an air curtain 42. The refrigerated trailer 10 may be coupled to a conventional truck assembly and related subassemblies such that trailer 10 transports refrigerated contents, especially food, from place to place, as will be understood by persons familiar with frozen or refrigerated food handling.

The insulated box 12 includes exterior walls 14, and interior walls 16 a and 16 b. Exterior walls 14 form an enclosure for housing the food contents (not shown in the figures). Interior walls 16 a and 16 b separate a freezer compartment 18, a cooler compartment 20, and a third compartment 22. Preferably, as shown in FIG. 1, freezer compartment 18 is located in the front-most section of the refrigerated trailer, cooler compartment 20 is located near the middle, and third compartment 22 is located at the rear. Preferably, interior walls 16 a and 16 b are movable.

Freezer compartment 18 includes a side door access 24 a. Cooler compartment 20 includes a side door access 24 b. Rear compartment 22 includes a side door access 24 c. Preferably, side doors 24 a, 24 b, and 24 c are formed on the left (that is, driver's) side. Refrigerated trailer 10 may also include a right side door 24 d for ease of access in some circumstances and locations. Refrigerated trailer 10 may also include a rear door 26. Located above side doors 24 a, 24 b, 24 c, and 24 d are air curtain units 42 a, 42 b, 42 c, and 42 d.

FIG. 2 shows a schematic elevational view of a portion of the trailer of FIG. 1. FIG. 2 contains a side door opening 45, a portion of the external wall 14 and the air curtain unit 42. In this embodiment, the air curtain unit 42 is positioned on the external wall 14 and inside the refrigerated trailer 14. The air curtain unit contains fans 44. The number of fans 44 contained within the air curtain unit 42 may vary and one skilled in the art of refrigerated trailer design would understand the present invention encompasses any number of fans 44 within the air curtain unit 42. The fans 44 take in internal, refrigerated air and blow the air downwardly over the door opening to limit air exchange between the insulated box and the outdoors. In a preferred embodiment, the air curtain is in manufactured by TMI, model #IBD2-42-155-MECDLR.

FIG. 3 shows a flowchart of components of the preferred embodiment. The refrigeration unit 28 contains an engine 34, a compressor 30 and a battery 32. Preferably, the refrigeration unit is conventional other than as described in the arrangement described herein. Other embodiments (not shown) may include the placement of contents of the refrigeration unit 28 in different locations. The battery 32 is electrically coupled to the inverter 38. The inverter 38 converts direct current (DC) from the battery 32 to alternating current (AC) to the air curtains 42. One skilled in the art could envision other arrangements to convert DC to AC power, and the illustrated arrangement is not intended to be limiting. In a preferred embodiment, a single inverter 38 is connected to multiple air curtains 42 a, 42 b, 42 c, and 42 d. In other embodiments, however, a single inverter 38 could be connected to a single air curtain 42 or multiple inverters could be connected to a single air curtain 42. In a preferred embodiment, the inverter is manufactured by Vector, model #VEC050D.

The air curtain units 42 a, 42 b, 42 c, and 42 d are connected to a thermostat 46 further connected to a temperature sensor 43. The temperature sensor 43 senses the ambient temperature and transfers this information to the thermostat 46. The thermostat 46 can be set to a specified temperature, wherein if the ambient temperature is below that set temperature the fans 44 of the air curtain 42 are disabled. In certain embodiments, each air curtain 42 is connected to its own thermostat 46. Alternatively each compartment 18, 20, and 22 within the insulated box 14 may contain its own thermostat; or multiple thermostats 46 may be connected to a single sensor 43; or preferably the temperature to which the thermostat is set is the internal temperature of the insulated box or a compartment within the insulated box. In a preferred embodiment, the thermostat is manufactured by Honeywell, model #tam813ge51.

The air curtain unit 42 is also connected to a switch 50 that detects when the side door 24 is open. It is preferable that each side door 24 a, 24 b, 24 c, and 24 d that contains an air curtain unit 42 a, 42 b, 42 c, and 42 d contain a switch 50 a, 50 b, 50 c, and 50 d. The switch 50 disables the fans 44 of the air curtain 42 when the side door 24 is closed. The possible types of switches that could be connected to the air curtain unit 42 to control the fans 44 when the side door is opened will be understood by persons familiar with refrigeration systems in view of the present disclosure.

The present invention is described by reference to a preferred embodiment. The present invention is not limited thereto, but rather encompasses structure and function as described in the claims. For example, details of the trailer, refrigeration unit, air curtain unit, and inverter are described, but the present invention is not limited to the particular structure or function of these components unless expressly stated in the claims. 

1. A refrigerated trailer comprising: an insulated box having a door opening and a side door associated with the door opening; a refrigeration unit for cooling air inside the insulated box, the refrigeration unit including an engine for supplying mechanical power to the refrigeration unit, batteries, and a compressor operatively coupled to the engine; an inverter electrically coupled to the batteries for supplying AC power; and an air curtain unit located above the side door, the air curtain unit including fans operating on AC power from the inverter; wherein the fans blow internal air downwardly over the door opening to limit air exchange between the insulated box and the outdoors.
 2. The refrigerated trailer of claim 1 further comprising a thermostat connected to a sensor that senses ambient temperature, wherein the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature.
 3. The refrigerated trailer of claim 1 wherein the inverter is located outside the insulated box near the refrigeration unit.
 4. The refrigerated trailer of claim 1 wherein the insulated box contains multiple compartments, each compartment separated from an adjacent compartment by an interior wall.
 5. The refrigerated trailer of claim 4 wherein the interior wall is movable, whereby sizes of the compartments are adjustable.
 6. The refrigerated trailer of claim 4 wherein the insulated box includes a freezer compartment and a cooler compartment, each one of the freezer compartments and cooler compartments having a side door.
 7. The refrigerated trailer of claim 6 wherein the freezer compartment is at the front of the insulated box and the cooler compartment is rearward of the freezer compartment.
 8. The refrigerated trailer of claim 7 wherein each compartment includes a thermostat connected to a sensor that senses ambient temperature and each compartment includes an air curtain unit whereby the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature.
 9. The refrigerated trailer of claim 7 wherein one compartment includes a thermostat connected to a sensor that senses ambient temperature and one compartment includes an air curtain unit whereby the fans of the air curtain unit are disabled if the ambient temperature is below a preset temperature.
 10. The refrigerated trailer of claim 6 wherein the insulated box includes a third compartment rearward of the cooler compartment, the third compartment having a side door.
 11. The refrigerated trailer of claim 10 wherein the freezer compartment is at the front of the insulated box, the third compartment is at the back of the insulated box, and the cooler compartment is between the freezer compartment and the third compartment.
 12. The refrigerated trailer of claim 1 wherein the refrigerated trailer contains three side doors on the left side of the insulated box and one side door on the right side of the insulated box.
 13. The refrigerated trailer of claim 1 wherein the fans of the air curtain unit are disabled when the side door is closed.
 14. The refrigerated trailer of claim 1 wherein the air curtain unit is located inside the insulated box.
 15. A method of maintaining temperature and humidity inside a refrigerated trailer, comprising the steps of: providing an insulated box having a door opening on a side of the insulated box and a side door; refrigerating air inside the insulated box, including operating a refrigeration unit that includes an engine, batteries, and a compressor operatively coupled to the engine; inverting DC current from the batteries to deliver AC power to fans of an air curtain unit located above the side door; blowing internal air via the fans downwardly from above an opening in the side door to limit air exchange between the enclosure and the outdoors; sensing an outdoor temperature; and disabling the fans if the outdoor temperature is below a preset temperature.
 16. The method of claim 15 further comprising disabling the fans of the air curtain unit when the side door is closed. 